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Post Info TOPIC: PTF11kx
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Title: Late-Time Spectral Observations of the Strongly Interacting Type Ia Supernova PTF11kx
Authors: Jeffrey M. Silverman, Peter E. Nugent, Avishay Gal-Yam, Mark Sullivan, D. Andrew Howell, Alexei V. Filippenko, Yen-Chen Pan, S. Bradley Cenko, Isobel M. Hook

PTF11kx was a Type Ia supernova (SN Ia) that showed time-variable absorption features, including saturated Ca II H&K lines that weakened and eventually went into emission. H{\alpha} was in emission, and its strength gradually increased, implying that the SN was undergoing significant interaction with its circumstellar medium (CSM). Many of these features were blueshifted slightly and showed a P-Cygni profile, likely indicating that the CSM was directly related to, and probably previously ejected by, the progenitor system itself. These and other observations led Dilday et al. (2012) to conclude that PTF11kx came from a symbiotic nova progenitor like RS Oph. In this work we extend the spectral coverage of PTF11kx to 124-680 rest-frame days past maximum brightness. These spectra of PTF11kx are dominated by H{\alpha} emission (with widths of ~2000 km/s), strong Ca II emission features (~10,000 km/s wide), and a blue "quasi-continuum" due to many overlapping narrow lines of Fe II. Emission from oxygen, He I, and Balmer lines higher than H{\alpha} is weak or completely absent at all epochs, leading to large observed H{\alpha}/H{\beta} intensity ratios. The broader (~2000 km/s) H{\alpha} emission appears to increase in strength with time for ~1 yr, but it subsequently decreases significantly along with the Ca II emission. Our latest spectrum also indicates the possibility of newly formed dust in the system as evidenced by a slight decrease in the red wing of H{\alpha}. During the same epochs, multiple narrow emission features from the CSM temporally vary in strength. The weakening of the H{\alpha} and Ca II emission at late times is possible evidence that the SN ejecta have overtaken the majority of the CSM and agrees with models of other strongly interacting SNe Ia. The varying narrow emission features, on the other hand, may indicate that the CSM is clumpy or consists of multiple thin shells.

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Blobrana


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Nova way to blow up a star

There is, it seems, more than one way to create an exploding star.
That's what scientists studying the origins of type 1a supernovae - important because they help to measure the accelerating expansion of the Universe and dark energy - have found.
A team, including Mark Sullivan of Oxford University's Department of Physics, has reported in Science observations that suggest weaker stellar explosions from giant stars contribute to some of these bright supernovae.
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Blobrana


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PTF 11kx
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Supernovae of the Same Brightness, Cut From Vastly Different Cosmic Cloth

Exploding stars called Type 1a supernova are ideal for measuring cosmic distance because they are bright enough to spot across the Universe and have relatively the same luminosity everywhere. Although astronomers have many theories about the kinds of star systems involved in these explosions (or progenitor systems), no one has ever directly observed one - until now.
In the August 24 issue of Science, the multi-institutional Palomar Transient Factory (PTF) team presents the first-ever direct observations of a Type 1a supernova progenitor system. Astronomers have collected evidence indicating that the progenitor system of a Type 1a supernova, called PTF 11kx, contains a red giant star. They also show that the system previously underwent at least one much smaller nova eruption before it ended its life in a destructive supernova. The system is located 600 million light years away in the constellation Lynx.
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PTF11kx
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Title: PTF11kx: A Type-Ia Supernova with a Symbiotic Nova Progenitor
Authors: B. Dilday, D. A. Howell, S. B. Cenko, J. M. Silverman, P. E. Nugent, M. Sullivan, S. Ben-Ami, L. Bildsten, M. Bolte, M. Endl, A. V. Filippenko, O. Gnat, A. Horesh, E. Hsiao, M. M. Kasliwal, D. Kirkman, K. Maguire, G. W. Marcy, K. Moore, Y. Pan, J. T. Parrent, P. Podsiadlowski, R. M. Quimby, A. Sternberg, N. Suzuki, D. R. Tytler, D. Xu, J. S. Bloom, A. Gal-Yam, I. M. Hook, S. R. Kulkarni, N. M. Law, E. O. Ofek, D. Polishook, D. Poznanski

There is a consensus that Type-Ia supernovae (SNe Ia) arise from the thermonuclear explosion of white dwarf stars that accrete matter from a binary companion. However, direct observation of SN Ia progenitors is lacking, and the precise nature of the binary companion remains uncertain. A temporal series of high-resolution optical spectra of the SN Ia PTF 11kx reveals a complex circumstellar environment that provides an unprecedentedly detailed view of the progenitor system. Multiple shells of circumsteller are detected and the SN ejecta are seen to interact with circumstellar material (CSM) starting 59 days after the explosion. These features are best described by a symbiotic nova progenitor, similar to RS Ophiuchi.

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